He has a bulbous head, curly hair, and ruddy face. His Princedom's colors are green and white, but his shardplate is painted red. It is decorated, including tassels on his helm.[4]

Sadeas is a cruel man who doesn't care about the lives of the bridgemen. He tried giving them shields once and took them away once the Parshendi began firing arrows into his soldiers and horses. On his orders, Gaz informs Kaladin that Sadeas has ordered the wounded men of Bridge Four to not receive food or pay for the duration of time they can't run bridges.[5]

Sadeas believes the Codes are a bunch of idealized nonsense, perceiving Gavilar Kholin's death as evidence that the Codes lead to ruin. His conviction for the Alethi way is indomitable, often not being able to reconcile with foreign ethics, such as the Codes and Dalinar's adherence to them.

Before Gavilar was assassinated, Sadeas and Dalinar were actually good friends. They maintain their respect for the other's abilities and appear cordial in person, but Sadeas secretly wants to outmaneuver Dalinar any way he can.[6]

Sadeas is first introduced when he is participating in a hunt out on the Plains with Dalinar, Dalinar's two sons, Renarin and Adolin, and the King of Alethkar, Elhokar. Sadeas taunts Dalinar over his lack of recent success in capturing gemhearts.[7]

When they arrive at the plateau where preparations for the hunt are under way, a chasmfiend appears on the plateau with all the courtiers and scribes, instead of the smaller plateau the hunt was supposed to take place on.

Dalinar, Adolin, and Elhokar immediately dash for the chasmfiend, hoping to kill it before it hurts any bystanders. From a distance, Sadeas uses his grandbow to weaken it while Dalinar and Adolin go for its legs and Elhokar distracts it. At some point in the battle, Elhokar's saddle strap breaks, throwing him to the ground. To save him from being crushed, Dalinar, with Shardplate-enhanced strength, catches the claw that would have otherwise crushed Elhokar. Adolin continues to cut off its legs and the chasmfiend is eventually unable to support its own weight. Elhokar summons his Shardblade again and uses it to kill the chasmfiend, then harvest its gemheart.

Back in the pavilion on the Plains, Elhokar and Sadeas are conversing when Dalinar approaches. Elhokar remarks to Dalinar that Sadeas has won three gemhearts in the last few weeks, followed up by chiding Dalinar for not having won any himself in that time. Both Elhokar and Sadeas make use of the topic to highlight many of Sadeas' achievements, which Dalinar calls into question, especially the act of sending unprotected bridgemen against the Parshendi. While Elhokar notes that Sadeas' bridge crews are more efficient than Dalinar's, and is why he is able to win so many gemhearts, Dalinar is of the opinion that Sadeas' method wastes lives, to which Sadeas retorts that Dalinar's reliance on wheels to maneuver his bridges is foolish.

Sadeas shows he has the mindset of most Alethi when he can't reconcile how Dalinar could have more important things to attend than the war and vengeance for Gavilar. While Dalinar takes a moralistic stance, a very un-Alethi way of thinking, Sadeas is only concerned with efficiency and results. From this point on the argument deteriorates until Sadeas insults Dalinar's sons, which is defused only by their mutual understanding for the safety of the king, not allowing their rivalry to descend into open conflict.

It is revealed Sadeas and Dalinar planned to manipulate Highprince Vamah into using more of Elhokar's Soulcasters, proving the two of them can work together in the best interests of the king. During the night of Gavilar's assassination, Sadeas acted as a decoy in an attempt to lead Szeth-son-son-Vallano away so Gavilar could escape. Dalinar tells Adolin that Sadeas has sworn to protect Elhokar at any cost.[6]

Dalinar has been investigating the cut girth strap on the king's saddle but at one particular king's feast, Elhokar announces that in light of the recent attempt on his life with the saddle, he is appointing Sadeas to Highprince of Information to investigate. This is to spite Dalinar who Elhokar believes is not taking the investigation seriously. Sadeas learned of Dalinar's request to be Highprince of War and this is Sadeas' way of outmaneuvering his opponent.[8]

Sadeas has been investigating the cut girth strap. Dalinar is insistent that Sadeas reveal the results of the investigation, which Adolin is convinced Sadeas will use the opportunity to incriminate Dalinar and turn the other Brightlords against him. This conviction is punctuated by Sadeas saying to Dalinar, “You asked for this, old friend.”[3]

Even Dalinar himself is tense at Sadeas' proclamation, given for all in attendance at the king's feast to hear. Sadeas had the strap sent to three different leather-workers who all concluded the strap had been cut – the leather was relatively new, as shown by its lack of flaking and cracking, and the tear too even.

To answer when it was cut, Sadeas interviewed many on the hunt and they all reported the same oddity: Dalinar and Elhokar storming off for the rock formation, leaving the two alone. This presented a problem, a problem that Sadeas discovered in the king's Plate: eight of the ten sapphires used to infuse the king's plate had been damaged. When Adolin (who still thinks Sadeas suspects Dalinar) protests, Sadeas notes how highly improbable this would be, since a simple fall from horseback wearing full Plate would not cause sufficient strain; only two or three sapphires usually need replacing after a battle. Someone must have sabotaged the Plate.

Next, Sadeas brings out one of the grooms in the king's employ, asking him to repeat what he told Sadeas in private. The groom confirmed the saddle had been checked over in Dalinar's camp, but also noted that the horse was wearing a different saddle on the way to Dalinar's camp from the king's. Sadeas proclaims that, in his personal opinion, the strap had been cut in Dalinar's camp to cast suspicion on Dalinar, and that Dalinar had no hand in the plot. This shocked both Adolin and Dalinar, both on their toes waiting for Sadeas to accuse Dalinar. Despite their rivalry, Sadeas does not want to claim a victory so easily.

Right after being vindicated, Dalinar proposed that Sadeas and he work together in capturing the Tower, a distant plateau near the Parshendi side of the Plains on which the Alethi have never won a gemheart. Dalinar suggests combining forces to which Sadeas agrees only after they can agree on the division of spoils, particularly any Blades which may be won.

As both men approached the Tower they could see the Parshendi had not yet extracted the gemheart from the chrysalis. Sadeas wanted to attack the Tower together, a “single grand wave of attack, across forty bridges!”[9] Dalinar refuses, saying he will attack only after Sadeas has made a landing point for Dalinar's bridge crews, citing the Codes again.

The plan worked well for a time. Sadeas managed to get his forces across the bridges and onto the Tower, carving out a landing platform for Dalinar to follow. Both forces were separated by the Parshendi, Sadeas to the west, Dalinar on the eastern edge, fighting inward. When another Parshendi force appeared behind Dalinar, Sadeas retreated to the northern plateau, pulling the eight bridge crews he'd leant to the Kholinar army with him and abandoning Dalinar Kholin.

Upon Sadeas' returning to camp he is met by Navani Kholin and says he must be the harbinger of grave news. He offers his condolences and claims he did all he could to save Dalinar but was ultimately overwhelmed by the Parshendi himself and forced back. Sadeas offers vengeance, claiming Dalinar was both a friend and an ally, shortly before Dalinar himself shows up, alive.

Sadeas attempts to reconcile with Dalinar, offering an apology that Dalinar accepts publicly. However, the two move close so no-one can overhear them and when Dalinar asks for an explanation, Sadeas claims he was upholding his oath: “Protect Elhokar. Protect this kingdom.” Gavilar obeyed the Codes and died from that “weakness.” Sadeas is of the mind that Elhokar is being influenced in a similar way by Dalinar's insistence on the Codes, beginning to worry when the king talks of retreating from the Plains, as Dalinar had wanted. Their friendship had been over a long time; Sadeas just wanted him gone.

Before leaving, Dalinar asked Sadeas to give him the members of Bridge Four to fulfill a promise he made to Kaladin. Sadeas refused the initial offers, claiming he would not give up his bridgemen for a thousand broams each. Dalinar summoned his Shardblade and drove it point-first in the earth before Sadeas and offered his Blade in exchange for every bridgemen in Sadeas' camp.[10] Sadeas appeared shocked but agreed, gaining the Blade he always desired.

After the Battle of the Tower, Sadeas is shown shortly after obtaining Dalinar'sShardblade Oathbringer, having it stuck into a table point first and staring at it in awe. Ialai comes into the room and complains about the table. Afterwards he tells her of how he intends to force the Alethi soldiers back into a full-out war, instead of a prolonged game of chasing down gemhearts and begins plotting with her, instructing her to send more spies into Dalinar's warcamp as well as preparing for any steps which may be required, including assassinating him.[1]

After a failed plateau assault on the Shattered Plains, Adolin is talking to Jakamav about his attempts at winning Shardblades and Shardplates through duels and his frustration at how no-one will rise to his challenge. Jakamav tells him that Sadeas has been making offers and promises to shardbearers in return for them turning down his challenges in order to stop his father's plans, and suggests Eranniv as one who might be more interested in fame than Sadeas' offers.[11]

Sadeas begins to undermine both Dalinar and Elhokar by using his swift bridge crews to go on plateau runs when it is not his turn in the rotation, arriving before the scheduled parties and then triumphantly throwing the harvested gemheart at their feet, before leaving.[12] This later develops to him simply pretending the gemheart had been lost, but secretly keeping it in order to further push the thrones authority.[13]

Sadeas is present at the duel between Adolin and Eranniv with his wife. He spends the duration speaking with his wife about their plots and about Dalinar's attempts to unite the Highprinces.[12]

Sadeas is later at the same winehouse that Adolin and Shallan visit together. Whilst waiting out the highstorm in the safety of the lighteyes' bunker Sadeas approaches Adolin and begins goading him about the Battle of the Tower and how he intends to do away with both Elhokar and Adolin. Sadeas is wearing uncut gems along his clothes, from a gemheart he had won earlier on the Shattered Plains but which he had claimed to have lost.[14]

After Adolin's duel with the 4 Shardbearers is won, Sadeas is forced to accept his boon of a challenge. However due to Kaladin interrupting, Adolin only gets to seek a challenge and not to pin down the time. As such, Sadeas takes the liberty of accepting to duel the young man a year after the date. He puts on an air of control and mirth after this, but in secret is terrified to see that Adolin is becoming another Blackthorn, like his father.[15]

On the last day before the Weeping Sadeas and his wife are taking a ride, supposedly for pleasure but in fact to assuage the extent of Sebarial's warcamp's industry. He speaks with his wife about Dalinar and Elhokar. Ialai believes they should seize the opportunity to attempt a coup on the Pinnacle, but Sadeas mentions it won't be necessary, and also points out the failure of their last assassin. After Highprince Aladar joins with Dalinar's forces, Sadeas is stunned, and thinks on the events for a long time, before ultimately deciding that it does not matter, as they will all die on the Shattered Plains and that they must set about deciding who will take their places as Highprinces.[16]